OP0083 HAND AND FOOT MRI IN CONTEMPORARY UNDIFFERENTIATED ARTHRITIS: IN WHICH PATIENTS IS MRI VALUABLE TO DETECT RHEUMATOID ARTHRITIS EARLY? – A LARGE PROSPECTIVE STUDY
Authors: N. den Hollander, M. Verstappen, N. Sidhu, E. van Mulligen, M. Reijnierse, A. van der Helm-van Mil
Journal: Annals of the Rheumatic Diseases (2022)

Background Identifying patients that will develop rheumatoid arthritis(RA) among those presenting with undifferentiated-arthritis(UA) remains a clinical dilemma. Although magnetic-resonance-imaging(MRI) is helpful according to EULAR-recommendations, this has only been determined in UA-patients not fulfilling 1987-RA-criteria, whilst part of these patients are currently considered as RA because they fulfill the 2010-criteria. Objectives We studied the predictive value of MRI for progression to RA in the current UA-population: i.e. not fulfilling RA-classification-criteria (neither 1987- or 2010-criteria), and not having an alternate diagnosis. Additionally, the value of MRI was studied in patients with a clinical diagnosis of UA, regardless of the classification-criteria. Methods Two UA-populations were studied: criteria-based-UA as described above(n=405) and expert-opinion-based-UA(n=564), i.e. UA indicated by treating rheumatologists. These patients were retrieved from a large cohort of consecutively included early arthritis patients that underwent contrast-enhanced MRI-scans of hand and foot at baseline. MRIs were scored for osteitis, synovitis and tenosynovitis. Patients were followed for RA-development during 1-year. Test-characteristics of MRI were determined separately for subgroups based on joint-involvement and autoantibody-status. Results Among criteria-based-UA-patients(n=405), 21% developed RA. MRI-detected synovitis and MRI-detected tenosynovitis were predictive. MRI-detected tenosynovitis was independently associated with RA-progression(OR 2.79; 95%CI 1.40-5.58), especially within ACPA-negative UA-patients(OR 2.91; 1.42-5.96). Prior risks of RA-development for UA-patients with mono-/oligo-/polyarthritis were 3%, 19%, 46%, respectively. MRI-results changed this risk most within the oligoarthritis-subgroup: PPV was 27% and NPV 93%. Similar results were found in expert-opinion-based-UA(n=564). Conclusion This large cohort-study showed that MRI is most valuable in ACPA-negative UA-patients with oligoarthritis; a negative MRI could aid in preventing overtreatment. Figure 1. Flowchart for criteria-based UA-patients showing pre-test and post-test predictive-value for RA-development (A) and percentages of patients within these subgroups (B). 1A) Flowchart with NPV and PPV for MRI-detected tenosynovitis within the specified groups. Pretest-probability of developing RA is shown as a percentage of patients fulfilling 1987 and/or 2010 RA-criteria. 1B) A total of 404 patients were studied, 15 patients were ACPA-positive(4%), 13 patients were ACPA-negative and RF-positive(3%), 376 patients were ACPA- and RF-negative(93%), from which 133 patients had monoarthritis (1 swollen joint, 33%), 169 patients had oligoarthritis (2-4 swollen joints, 42%) and 74 patients had polyarthritis (more than 4 joints, 18%). 1 patient is missing in this analysis due to missing outcome for MRI-detected tenosynovitis, this patient belonged in the oligoarthritis group. UA, Undifferentiated arthritis; RA, Rheumatoid Arthritis; ACPA, Anti-Citrullinated Peptide Antibodies (considered positive if ≥10U/mL); RF, Rheumatoid Factor (considered positive if ≥5.0IU/mL); MRI-TS, MRI detected tenosynovitis; NPV, negative predictive value; PPV, positive predictive value; Swollen joints, based on a 68-swollen joint count. Disclosure of Interests None declared.